(a) Field of the Invention
The present invention relates to a thin film transistor array panel and a manufacturing method thereof.
(b) Description of the Related Art
A liquid crystal display (LCD) is one of the most widely used flat panel displays. An LCD includes two panels provided with field-generating electrodes such as pixel electrodes and a common electrode, and a liquid crystal (LC) layer interposed therebetween. The LCD displays images by applying voltages to the field-generating electrodes to generate an electrical field in the LC layer, which determines orientations of LC molecules in the LC layer to adjust polarization of incident light.
Among LCDs including field-generating electrodes on respective panels, one kind of LCD provides a plurality of pixel electrodes arranged in a matrix on one panel, and a common electrode covering an entire surface of the other panel. The image display of the LCD is accomplished by applying individual voltages to the respective pixel electrodes. Application of the individual voltages is achieved by utilizing a plurality of three-terminal thin film transistors (TFTs) which are connected to the respective pixel electrodes. A plurality of gate lines is provided for transmitting control signals to the TFTs, and a plurality of data lines is provided for transmitting voltages to be applied to the pixel electrodes.
One panel for an LCD typically includes a layered structure having several conductive layers and insulating layers. Gate lines, data lines, and a pixel electrodes are formed from different conductors, and the insulating layers are interposed therebetween to insulate the different conductors from each other.
Typically, an H2 cleaning process is used to protect the exposed channel portion of the semiconductor and to remove impurities remaining on the channel portion after forming the pixel electrode. However, the metal components of indium zinc oxide (IZO) or indium tin oxide (ITO) of the pixel electrode react when executing the H2 cleaning process and this results in the formation of opaque metal particles. These metal particles adhere to the surface of the pixel electrode, which reduces the transmittance of the pixel.
To prevent this problem, the H2 cleaning process is sometimes omitted. In this case, a leakage current is generated in the semiconductor, such that the electrical characteristics of the thin film transistor are deteriorated.
Furthermore, when silicon nitride (SiNx) is deposited on an IZO or ITO transparent electrode, gases such as H2 and SiH4 are used, which results in the generation of opaque metal materials.